[Freeciv-Dev] (PR#4564) Ground units can destroy planes!

["Guest" <rt-guest@xxxxxxxxxxxxxx>]

When a plane attack a ground unit, if the plane lost, it is destroyed.
That's really not realistic. When a plane bombard an unit and fail, it
should only lose move points and hit points only in paticular situation.
I think a combat between a plane and a ground/sea unit should be like this.

Role the dice 8 times:
For each roll, if the plane win, the attacked unit lose one hit point.
If the attacked unit win, ther is different cases:
  - the defender is in a city with SDI/SAM: the ait unit lose one hit point